The present invention relates to a system for alerting passengers, particularly school children, of the impending arrival of a school bus.
In a rural area, a school bus travels many miles in picking up students along its particular route. The students to be picked up can live in a diverse range of homes. Some students live close together and in turn can cluster at a common bus stop while others live away from the road, in fact sometimes so far away that the road cannot be seen. In either situation it would be desirable if the children could know in advance that the school bus was approaching and have time to gather their belongings before journeying to the bus stop or to the road where the bus will stop. During the winter and in rainy weather it would be particularly desirable for the students to know with a reasonable degree of certainty of the time when the bus will arrive so that they will have time to dress for the weather before starting out. Also, since school buses all too commonly become stuck in snow or ice along the bus route, the students would not have to wait an undue period of time for the bus, not knowing when or if it will arrive.
Parents in school systems have been aware of this problem for some time and have attempted to solve it by equipping the school buses with transmitters which would send out a signal which could be received in the home to alert the school children. While this appears to be an easy solution to the problem, it has been anything but that. Many of the proposed systems have been far too complicated and in turn too expensive to be practical. Also, the receivers in the home were too complicated, or subject to being incorrectly adjusted, so that the signal was either not received or not received early enough to give the children time to prepare to leave for the bus.
In U.S. Pat. No. 3,560,916, issued to Buckingham et al. Feb. 12, 1966, a transmitter is provided on the bus having a frequency-determining element which was controlled by the odometer cable. As the bus traveled along the route incremental changes in the odometer reading caused the transmitted signal to increase in frequency by a predetermined amount. Each home along the route had a receiver with a precisely tuned circuit which could recognize the particular frequency corresponding to the position of the bus at that time or at the time needed to provide warning for the school children to prepare to leave to meet the bus. Both the transmitter and receiver in this system were extremely complicated and expensive which caused the system to not be accepted.
In U.S. Pat. No. 4,325,057, issued to Bishop on Apr. 13, 1982, a school bus approach system was disclosed in which the bus transmits a signal on a frequency corresponding to the route that the bus would travel. The home would have a receiver capable of receiving this signal and alerting the school children of the pending arrival of the bus. The bus driver could select through a switch the particular frequency the transmitter would send on, corresponding to the route the bus would travel. A receiver was provided for each home along that particular route which was capable of detecting the particular signal sent by the bus. The receiver at the home had a sensitivity control to be used to adjust the receiver so that it would only emit a warning signal when the bus was at a particular distance from the home which would provide the children with sufficient time to prepare to board the bus. Since the sensitivity control determined the point when the receiver would activate visual or audible alarm alerting the students of the approach of the bus, the sensitivity control became a source of error. If the sensitivity control was adjusted improperly so that it required too strong a signal, then the bus would be too close to the home before the receiver would become activated. On the other hand, if the control was set so that the receiver was too sensitive, then the purpose of the system was defeated since the children would prepare and expose themselves to inclement weather for an unnecessarily long time before the bus arrived.
Another serious deficiency in the Bishop system was that the bus was limited in the number of frequencies upon which it could transmit a signal. Both the receiver and transmitter were crystal controlled and only a small number of frequencies were available for use. Also, the patent provides no teaching as to how students of different ages or in different grades in the same school could differentiate between buses traveling on the same route. The distinguishing feature was the bus route and not a signal specific to each bus.